1. Field of the Invention
This invention relates to heat sinks for electronic devices and in particular to a new and improved method of fabricating a diamond heat sink.
2. Description of the Prior Art
The diamond heat sink has been found to be a very effective means of removing heat from adjacent components, such as small semiconductor diode chips. Typically, a diode chip is attached to a diamond which is imbedded in a metallic base, the diamond and metallic base being referred to as the diamond heat sink. When power is applied to the diode chip, it generates heat which, unless it is removed from the chip, can adversely affect useful life and operating performance. Since the diamond has very high thermal conductivity, it transmits the heat generated by the diode chip to the metallic base which in turn dissipates the heat to its surroundings.
Some performance deficiencies have been encountered with diamond heat sinks, however, as a result of the methods of attaching the diamond to its metallic base. One currently used method involves brazing the diamond to the surface of the metallic base. Since only one face of the diamond is in contact with the metallic base, however, the amount of heat that can be transmitted to the base is limited. Also, the filler metal used in the brazing interferes with the ability of the diamond to transmit heat to the base and thus reduces the efficiency of the heat sink.
Another currently used method of attaching the diamond to its metallic base is by hot pressing it into the base. This method provides greater contact and thus an increased capacity to transmit heat since the sides as well as the bottom face of the diamond are surrounded by the metallic base. However, since the hot pressing of the diamond into its base is a mechanical process, gaps tend to form between the diamond and the base which results in reduced heat transmitting efficiency. Also, because of the force required to press the diamond into its base, the metalized coating on the diamond, required for an electrical path between the diode chip and the base, is sometimes sheared. Further, the hot pressing may cause the metal in the metallic base, which is usually copper, to overflow and distort the surface of the base as it is displaced by the diamond.
In view of the above mentioned problems, it is therefore an object of the present invention to provide a method of fabricating a diamond heat sink which provides essentially gapless contact between the diamond and its base, thereby improving heat transfer efficiency between the two.
Another object of the present invention is to provide a method of fabricating a diamond heat sink which maintains a proper electrical path across the diamond metalized for that purpose.
Yet another object of the present invention is to provide a method of fabrication which does not distort the surface of the metallic base.